A number of devices have been proposed for the aligning of cutting-type tools or for precise measurement of a particular dimension of a workpiece. The most common of the devices currently in use for fulfilling the function of the stable measuring platform is similar to that disclosed in Sigg, U.S. Pat. No. 4,596,076. A three point contact with the exterior of the workpiece is shown, however, the Sigg device is designed merely for the measurement of the diameter of the piece within the grasp of the device. A modified Sigg device has a dial indicator positioned on one of the support arms, angled so that a cutting insert position may be accurately located. This modified device, however, is ungainly and has poor balance, requiring the operator of the cutting machine to hold the measuring device while aligning the cutting insert. This allows for a greater degree of inaccuracy, because of movement by the user during measurement.
Other devices are adapted to be clamped to a surface near the cutting edges to be aligned, as disclosed in Cox, et. al., U.S. Pat. No. 3,546,781. Such a device has a lesser degree of accuracy, because inaccuracy in the measurement is heightened by inaccurate placement of the measuring device on the cutting tool or some exterior surface. Additionally, if the measuring device is mounted on a surface that is not the actual cutting tool, such as the body of the cutting machine, inaccuracy is increased because of play or deviation in the mounting of the cutting tool within the body of the cutting machine.
Portability and ease of use are also important considerations. A measuring device should be capable of being used on the cutting machine itself and not require removal of the cutting tool for calibration. Similarly, the device, even though portable, should have a high degree of accuracy based on careful mounting of the measuring device on the cutting tool. Mason, U.S. Pat. No. 4,222,172, and Wilson, U.S. Pat. No. 3,564,721, disclose devices that have little portability and capability for accurate placement of the workpiece within the measuring chamber.